1. Field of Invention
The present invention relates to a fuel injection control of a fuel injection engine and, more particularly, a fuel injection type general-purpose engine capable of setting a fuel injection quantity and an injection timing with a simple structure.
2. Description of Related Art
In general, general-purpose engines adopt a carburetor in a fuel system, and the so-called xe2x80x9cmagnet ignition systemxe2x80x9d in the ignition system in order to suppress the manufacturing cost of the engine.
The magnet ignition system includes: a flywheel mounted on the crankshaft of the engine; a magnet disposed on the flywheel; and an ignition coil. The ignition is effected by the high voltage which is induced in the ignition coil by the magnet.
However, in the case that a carburetor type engine is changed into a fuel injection engine which is superior in startability, operability just after start and exhaust gas emission, newly added parts and complicated structures are needed.
In order to determine the fuel injection quantity and the injection timing of the fuel injection engine, it is necessary to discriminate the speed (the rotating speed) and the phase of the engine. As this discrimination means, there are usually used a pulsar coil and a rotary disc having a number of protrusions on its outer circumference. In the fuel injection type, therefore, in addition to the ignition coil, there are newly needed parts such as the pulsar coil and the rotary disc, inviting a complicated structure and increased cost.
Accordingly, it is an object of the present invention to provide a fuel injection engine which can make simple and inexpensive means for determining a fuel injection quantity and an injection timing.
According to the first aspect of the present invention, a fuel injection engine comprises: a fuel injector for injecting a fuel into intake air; an ignition coil for activating an ignition plug by generating an ignition current synchronized with the rotation of the engine; and an injection control device for controlling the injection quantity and the injection timing of the fuel injector, wherein the injection control device determines the engine speed and phase by using an ignition current extracted from a primary coil side of the ignition coil to control the injection quantity and the injection timing of the fuel injector.
According to the fuel injection engine, the ignition current from the ignition coil can be used as the timing signal to control the injection quantity and the injection timing of the fuel injector. Therefore, the pulsar coil and the rotary disc, as have been essential for the fuel injection engine of the prior art, can be dispensed with to reduce the number of parts and to lower the manufacturing cost.
Preferably, the engine is a V-type 2-cylinder engine, and the ignition coil is provided for each cylinder. Thus, the timing signals of unequal pitches out of phase shifts of 90 degrees and 270 degrees are obtained from the ignition coils which are provided for the V-type 2-cylinder engine having a bank angle of 90 degrees, for example. By using these unequal pitch signals, therefore, the cylinder can be discriminated without any other discrimination circuit so that the injection quantity and the injection timing of the fuel injector can be controlled independently for any of the cylinders.
Preferably, the injection control device is using a microcomputer.
Preferably, the fuel injection engine further comprises: a flywheel mounted on a crankshaft; and a magnet disposed on the rotary face of the flywheel, wherein the ignition coils having a predetermined clearance from the magnet are disposed to be circumferentially spaced by a predetermined angle on the engine.
Preferably, the magnet is disposed on the outer circumference of the flywheel, and the ignition coils disposed outside of the flywheel have a core, and the core has a predetermined clearance from the magnet.